I'll answer this to the best of my ability, but you can always call your surgeon and ask on the ostomies forum on healingwell.
It is possible to still have active ulcerative colitis inflammation within the small portion of your rectum that remains after your colectomy surgery. So, you might still see mucus and blood as a consequence of that remaining inflammation and expel it multiple times per day.
Generally, you have two choices:
1.) You can keep the end-ileo when you are happy with it, and they'd do another surgery to remove the remaining rectum and close the
opening up.
2.) The j-pouch is the other choice, which would enable you to sit on the toilet and have a bm. They make a pouch out of the end of your small intestine and attach it to the sphincter muscles. As UC is limited to the large intestine, there should be no further inflammation.
You can read up on articles regarding the procedure -
There are also some good blogs out there that really helped get a handle on what the process is like -